1. Field of the Invention
The present general inventive concept relates to a digital broadcasting transmission and/or reception system and a signal processing method thereof, and more particularly, to a digital broadcasting transmission and/or reception system and a signal processing method thereof capable of improving reception performance of a reception system by inserting and transmitting a known sequence into a VSB (Vestigial Side Bands) data stream.
2. Description of the Related Art
Generally, an ATSC (Advanced Television Systems Committee) VSB mode, which is the U.S. terrestrial digital broadcasting system, is a single carrier method, and a field sync is used in a unit of 312 segments.
FIG. I is a block diagram for displaying a transceiver including a digital broadcasting transmitter and a digital broadcasting receiver according to an ATSC DTV standard as a general U.S. terrestrial digital broadcasting system.
Referring to FIG. 1, the digital broadcasting transmitter has a randomizer 110 for randomizing an MPEG-2 transport stream (TS), a Reed-Solomon (hereafter referred to as ‘RS’) encoder 120 for adding Reed-Solomon parity bytes into the MPEG-2 transport stream to correct a bit error caused by a channel characteristic in a transporting process, an interleaver 130 for interleaving the RS encoded data according to a certain pattern, and a Trellis encoder for performing trellis encoding by a ⅔-rate to the interleaved data and 8-level symbol mapping to perform error correcting coding for the MPEG-2 transport stream.
The digital broadcasting transmitter also includes a MUX 150 for inserting a segment sync and a field sync to the error correction coded data, and a Modulator/RF up-converter 160 for inserting a pilot tone after adding a certain DC value in a data symbol that the segment sync and the field sync are inserted, and for performing VSB modulation and up-converting to and transmitting an RF channel band signal.
Therefore, the digital broadcasting transmitter randomizes the MPEG-2 transport stream, outer-codes the randomized data through the RS encoder 120 which is an outer coder, and distributes the coded data through the interleaver 130. Also, the digital broadcasting transmitter inner-codes the interleaved data through Trellis encoder 140 by a 12 symbol rate, maps the inner coded data by an 8 symbol rate, and then inserts the field sync, the segment sync, and the pilot tone for VSB modulation, and converts to and transmits the RF signal.
Meanwhile, the digital broadcasting receiver includes a tuner/IF 210 for converting a received RF signal to a baseband signal, and a demodulator 220 for synchronizing and demodulating the converted baseband signal, an equalizer 230 for compensating the demodulated signal for channel distortion caused by a multipath, a Trellis decoder 240 for applying error correction and decoding with respect to the equalized signal, a deinterleaver 250 for rearranging the dispersed data by the interleaver 130 of the digital broadcasting transmitter, an RS decoder 260 for correcting errors, a derandomizer 270 for outputting the MPEG-2 transmission stream by derandomizing the corrected data through RS decoder 260.
Hence, an operation sequence of the digital broadcasting receiver of FIG. 1 is a reverse order of the digital broadcasting transmitter, that is, down-converting the RF signal to the baseband signal, demodulating and equalizing the down-converted signal, performing channel decoding, and restoring the original signal.
FIG. 2 shows a VSB data frame interleaved with a segment sync signal and a field sync signal for the U.S. digital broadcasting (8-VSB) system. Each data frame consists of two data fields, and each field contains a 1 field sync segment and a 312 data segment. In the VSB data frame, the segment is equivalent to one MPEG-2 packet, and can have a 4-symbol segment sync and 828 data symbols.
In FIG. 2, the segment sync signal and field sync signal for sync signals are used for synchronization and equalization at the digital broadcasting receiver. That is, the field sync signal and segment sync signal are data between the digital broadcasting transmitter and receiver to be used as reference signals in equalization by the receiver.
The VSB mode of the U.S. terrestrial digital broadcasting system depicted in FIG. I adopts a single carrier method, which has a weakness in multipath fading channel environments with Doppler. Therefore, performance of the digital broadcasting receiver depends on a capacity of the equalizer for eliminating such multipath.
However, the existing transmitting frame of FIG. 2 has a weakness in degrading an equalization performance due to a low frequency in appearance, since the field sync, that is a reference signal of an equalizer, appears once every 313 segments.
That is, it is difficult to estimate channels and to equalize the received signal by eliminating the multipath using an existing equalizer and such small data described above. Due to this, the conventional digital broadcasting receiver has a problem of reception performance deterioration in poor channel environment, particularly in Doppler fading channel environment.